/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 *
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 *
 *
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 *
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address:
 *
 *  Pearson Education, Inc.
 *  Rights and Contracts Department
 *  75 Arlington Street, Suite 300
 *  Boston, MA 02216
 *  Fax: (617) 848-7047
*/


#ifndef QUEUE_H
#define QUEUE_H

//NB: if change the interface in this file, also update Queue_interface.h!!!!
//    and int-Queue.h

#include <iostream>

// function template declaration must precede friend declaration in Queue
template <class T> class Queue;
template <class T>
std::ostream& operator<<(std::ostream&, const Queue<T>&);

//begin{basic-Queue}
template <class Type> class Queue
{
//end{basic-Queue}
	friend std::ostream&
	operator<< <Type> (std::ostream&, const Queue<Type>&);
public:
	Queue(): head(0), tail(0) { }

	// construct a Queue from a pair of iterators on some sequence
	template <class It> Queue(It, It): head(0), tail(0)
	{
		copy_elems(beg, end);
	}

	// copy control to manage pointers to QueueItems in the Queue
	Queue(const Queue& Q): head(0), tail(0)
	{
		copy_elems(Q);
	}
	Queue& operator=(const Queue&);
	~Queue()
	{
		destroy();
	}
	// replace current Queue by contents delimited by a pair of iterators
	// MS: requires member templates to be defined inside the class body
	template <class Iter> void assign(Iter beg, Iter end)
	{
		destroy();
		copy_elems(beg, end);
	}

	// return element from head of Queue
	// unchecked operation: front on an empty Queue is undefined
	Type& front()
	{
		return head->item;
	}
	const Type front() const
	{
		return head->item;
	}

	void push(const Type&); // add element to back of Queue
	void pop();             // remove element from head of Queue

	bool empty() const      // true if no elements in the Queue
	{
		return head == 0;
	}
//begin{basic-Queue}
	// interface functions to Queue are unchanged
private:
	// public members are ok: QueueItem is a private member of Queue
	// only Queue and its friends may access the members of QueueItem
	struct QueueItem {
		// workaround: MS Compiler requires nested class members
		// to be defined inside the class
		QueueItem(const Type& t): item(t), next(0) { }
		Type item;           // value stored in this element
		QueueItem* next;     // pointer to next element in the Queue
	};

	QueueItem* head;   // pointer to first element in Queue
	QueueItem* tail;   // pointer to last element in Queue
//end{basic-Queue}

	// utility functions used by copy constructor, assignment and destructor
	void destroy();          // delete all the elements
	void copy_elems(const Queue&); // copy all elements from parameter
private:
	// copy all elements from input range denoted by iterator pair
	// MS: requires member templates to be defined inside the class body
	template <class Iter> void copy_elems(Iter beg, Iter end)
	{
		while (beg != end) {
			push(*beg);
			++beg;
		}
	}
//begin{basic-Queue}
};
//end{basic-Queue}

// Inclusion Compilation Model: include member function definitions as well
#include "MS_Queue.cpp"

#endif

